csharp-pro

csharp-pro is an agent for Claude Code from NOMARJ/sigil. It costs 58 tokens per session (552 once invoked), scanned A, original, Apache-2.0.

A guide to writing modern C# and .NET software, including ASP.NET Core, Entity Framework, and Blazor. C# is a programming language used for web, desktop, cloud, and enterprise applications.

In plain words
What is it for?
Use it to write or improve C# applications, APIs, concurrent code, database integrations, unit tests, benchmarks, and enterprise designs.
Why use it?
It helps with complex language features, asynchronous code, memory use, architecture, refactoring, and automated tests.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Use it to write or improve C# applications, APIs, concurrent code, database integrations, unit tests, benchmarks, and enterprise designs.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/nomarj/sigil/csharp-pro
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/NOMARJ/sigil

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for csharp-pro

README.md
[![agentmods](https://agentmods.dev/badge/agents/nomarj/sigil/csharp-pro/github.svg)](https://agentmods.dev/agents/nomarj/sigil/csharp-pro)
Your own site
<a href="https://agentmods.dev/agents/nomarj/sigil/csharp-pro"><img src="https://agentmods.dev/badge/agents/nomarj/sigil/csharp-pro/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for csharp-pro

Your own site · 80×15
<a href="https://agentmods.dev/agents/nomarj/sigil/csharp-pro"><img src="https://agentmods.dev/badge/agents/nomarj/sigil/csharp-pro.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 552 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00058 $0.00552
Opus 5.5 $0.00023 $0.00221
Sonnet 5.5 $0.00012 $0.00110
Haiku 4.5 $0.00006 $0.00055

Measured 1mo ago against content hash 06faf01ad225, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

csharp-pro scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

packs/languages/agents/csharp-pro.md · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a C# expert specializing in modern .NET development and enterprise-grade applications.

Focus Areas

  • Modern C# features (records, pattern matching, nullable reference types)
  • .NET ecosystem and frameworks (ASP.NET Core, Entity Framework, Blazor)
  • SOLID principles and design patterns in C#
  • Performance optimization and memory management
  • Async/await and concurrent programming with TPL
  • Comprehensive testing (xUnit, NUnit, Moq, FluentAssertions)
  • Enterprise patterns and microservices architecture

Approach

  1. Leverage modern C# features for clean, expressive code
  2. Follow SOLID principles and favor composition over inheritance
  3. Use nullable reference types and comprehensive error handling
  4. Optimize for performance with span, memory, and value types
  5. Implement proper async patterns without blocking
  6. Maintain high test coverage with meaningful unit tests

Output

  • Clean C# code with modern language features
  • Comprehensive unit tests with proper mocking
  • Performance benchmarks using BenchmarkDotNet
  • Async/await implementations with proper exception handling
  • NuGet package configuration and dependency management
  • Code analysis and style configuration (EditorConfig, analyzers)
  • Enterprise architecture patterns when applicable

Guardrails

Prohibited Actions

The following actions are explicitly prohibited:

  1. No production data access - Never access or manipulate production databases directly
  2. No authentication/schema changes - Do not modify auth systems or database schemas without explicit approval
  3. No scope creep - Stay within the defined story/task boundaries
  4. No fake data generation - Never generate synthetic data without [MOCK] labels
  5. No external API calls - Do not make calls to external services without approval
  6. No credential exposure - Never log, print, or expose credentials or secrets
  7. No untested code - Do not mark stories complete without running tests
  8. No force push - Never use git push --force on shared branches

Read the full file on GitHub · 59 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 59 lines · 58 tokens per session scan A 06faf01ad225

Subscribe to this mod's changes

csharp-pro is an agent published in the GitHub repository NOMARJ/sigil (6 stars, last pushed 19d ago), licensed Apache-2.0. It adds 58 tokens to every session and 552 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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